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Computer Network Assignment A131202
'INTRODUCTION' Computer networking, once strictly the domain of technologists and characterized by experimentation with a diverse range of protocols and network designs for machine-to-machine communication, has rapidly standardized in recent years. This standardization is most easily apparent in the ubiquitous Internet built predominantly on the now dominant combination of Ethernet and TCP/IP protocols. Standardization and the diffusion of the Internet has given rise to a lay experience of computer networking and an accompanying lay vocabulary of computer networking concepts. The lay experience of computer networking centers on human to- human exchange via communication software systems such as e-mail, Listserv, and UseNet News that support the sharing of meaningful symbolic information encoded in human language, sounds, and visual images. Two streams of discourse addressing computer networks exist simultaneously: (a) a formal, technical, scientific discourse shared primarily among computer science professionals and (b) a generic discourse based on the common understanding of the lay public, who nevertheless have extensive experience using computer systems that are attached to networks. In the past, when the principal users of computer networks were professional technologists and computer scientists, the technical language of computer science predominated. However, as computing has radically diffused throughout society, the priority of these two distinctive systems of language and experience has, to an extent, reversed. 'BACKGROUND' The Internet of today is a complex and anarchic seeming worldwide network of computer networks. Applications such as electronic mail and the World Wide Web seem on their way to becoming as ubiquitous as the telephone and television in earlier generations. With hundreds of millions of users, the Internet of 2002 is larger than any corporation or government entity in history. Indeed, the Net of the 2000s has more users than the United States or European Union has citizens. How the Internet became what it is today is a story with long and tangled roots. Nobody planned the Internet as it exists today, and nobody controls it in any usual sense of the word. Instead the Internet sprang from the visionary seeds planted by the forethought of men such as Vannevar Bush and J. C. R. Licklider. The Net thrived quietly for three decades under the gentle guidance of Jon Postel and others, and then sprang into worldwide prominence in the 1990s with the advent of the World Wide Web. 'BENEFITS' Connectivity and Communication Networks connect computers and the users of those computers. Individuals within a building or work group can be connected into local area networks (LANs); LANs in distant locations can be interconnected into larger wide ''area networks (WANs). Once' connected, it is possible for network users to communicate with each other using technologies such as electronic mail. This makes the transmission of business (or non-business) information easier, more efficient and less expensive than it would be without the network. Data Sharing One of the most important uses of networking is to allow the sharing of data. Before networking was common, an accounting employee who wanted to prepare a report for her manager would have to produce it on his PC, put it on a floppy disk, and then walk it over to the manager, who would transfer the data to her PC's hard disk. (This sort of “shoe-based network” was sometimes sarcastically called a “sneakernet”.) True networking allows thousands of employees to share data much more easily and quickly than this. More so, it makes possible applications that rely on the ability of many people to access and share the same data, such as databases, group software development, and much more. Intranets and extranets can be used to distribute corporate information between sites and to business partners. Hardware Sharing Networks facilitate the sharing of hardware devices. For example, instead of giving each of 10 employees in a department an expensive color printer (or resorting to the “sneakernet” again), one printer can be placed on the network for everyone to share. Internet Access The Internet is itself an enormous network, so whenever you access the Internet, you are using a network. The significance of the Internet on modern society is hard to exaggerate, especially for those of us in technical fields. Internet Access Sharing Small computer networks allow multiple users to share a single Internet connection. Special hardware devices allow the bandwidth of the connection to be easily allocated to various individuals as they need it, and permit an organization to purchase one high- speed connection instead of many slower ones. Data Security and Management In a business environment, a network allows the administrators to much better manage the company's critical data. Instead of having this data spread over dozens or even hundreds of small computers in a haphazard fashion as their users create it, data can be centralized on shared servers. This makes it easy for everyone to find the data, makes it possible for the administrators to ensure that the data is regularly backed up, and also allows for the implementation of security measures to control who can read or change various pieces of critical information. Performance Enhancement and Balancing Under some circumstances, a network can be used to enhance the overall performance of some applications by distributing the computation tasks to various computers on the network. Entertainment Networks facilitate many types of games and entertainment. The Internet itself offers many sources of entertainment, of course. In addition, many multi-player games exist that operate over a local area network. Many home networks are set up for this reason, and gaming across wide area networks (including the Internet) has also become quite popular. 'WHAT IS CLASSIFICATION OF NETWORK' Local area network A local area network (LAN) is a network that connects computers and devices in a limited geographical area such as home, school, computer laboratory, office building, or closely positioned group of buildings. Each computer or device on the network is a node. Current wired LANs are most likely to be based on Ethernet technology, although new standards like ITU-T G.hn also provide a way to create a wired LAN using existing home wires (coaxial cables, phone lines and power lines). All interconnected devices must understand the network layer (layer 3), because they are handling multiple subnets (the different colors). Those inside the library, which have only 10/100 Mbit/s Ethernet connections to the user device and a Gigabit Ethernet connection to the central router, could be called "layer 3 switches" because they only have Ethernet interfaces and must understand IP. It would be more correct to call them access routers, where the router at the top is a distribution router that connects to the Internet and academic networks' customer access routers. The defining characteristics of LANs, in contrast to WANs (Wide Area Networks), include their higher data transfer rates, smaller geographic range, and no need for leased telecommunication lines. Current Ethernet or other IEEE 802.3 LAN technologies operate at speeds up to 10 Gbit/s. This is the data transfer rate. IEEE has projects investigating the standardization of 40 and 100 Gbit/s. Personal area network A personal area network (PAN) is a computer network used for communication among computer and different information technological devices close to one person. Some examples of devices that are used in a PAN are personal computers, printers, fax machines, telephones, PDAs, scanners, and even video game consoles. A PAN may include wired and wireless devices. The reach of a PAN typically extends to 10 meters A wired PAN is usually constructed with USB and Firewire connections while technologies such as Bluetooth and infrared communication typically form a wireless PAN. Home area network A home area network (HAN) is a residential LAN which is used for communication between digital devices typically deployed in the home, usually a small number of personal computers and accessories, such as printers and mobile computing devices. An important function is the sharing of Internet access, often a broadband service through a CATV or Digital Subscriber Line (DSL) provider. It can also be referred as an office area network (OAN). Wide area network A wide area network (WAN) is a computer network that covers a large geographic area such as a city, country, or spans even intercontinental distances, using a communications channel that combines many types of media such as telephone lines, cables, and air waves. A WAN often uses transmission facilities provided by common carriers, such as telephone companies. WAN technologies generally function at the lower three layers of the OSI reference model : the physical layer the data link layer, and the network layer. Campus network A campus network is a computer network made up of an interconnection of local area networks (LAN's) within a limited geographical area. The networking equipments (switches, routers) and transmission media (optical fiber, copper plant, Cat5 cabling etc.) are almost entirely owned (by the campus tenant / owner: an enterprise, university, government etc.). In the case of a university campus-based campus network, the network is likely to link a variety of campus buildings including; academic departments, the university library and student residence halls.